Method and apparatus for checking knots



March 5, 1968 E. FELIX 3,371,568

METHOD AND APPARATUS FOR CHECKING KNOTS I Filed March 28, 1966 2Sheets-Sheet 1 -INVENTOIQ ERNST FELIX A? T TORNEVS E. FELIX METHOD ANDAPPARATUS FOR CHECKING KNOTS March 5, 1968 2 Sheets-Sheet Filed March28, 1966 //\l\/ENTOR "-ERNST FELIX 5y @ORNEYS United States Patent3,371,568 METHOD AND APPARATUS FOR ECKING KNOTS Ernst Felix, UsteSwitzerland, assignor to Zellweger Ltd., Uster, Switzerland, acorporation of Switzerland Filed Mar. 28, 1966, Scr. No. 537,884 Claimspriority, applicatioii6 svgistzerland, Mar. 31, 1965, 8/

10 Clainis. (11. 83-13) ABSTRACT OF THE DISCLOSURE In the textileindustry, and particularly during the spooling process, the knotting oftwo threads together is a frequent operation, particularly when spoolingthreads. -In the case of manually operated spooling machines theknotting process is done manually, whereby visual checking of the knotis possible. However, automatic spooling machines have lately appearedon the market wherein visual checking is no longer possible. Sincederangements often occur during the knotting operation, it is necessarythat the knots be checked. Among the chief derangements that occur areeither incomplete severance or lack of severance of the so-calledremnant threads at the time of knotting so that for some reason a thirdthread is knotted incorrectly. Etficacious checking of these knots musttherefore check both the size of the knot and the immediate vicinity ofthe knot to detect the presence of the remnant threads.

Heretofore, mechanical knot monitors have been known which have beenadjusted to a particular size of knot so that when that size is exceededa signal is sent out to sever the thread near the oversized knot toremove the defective portion. Because of this, the threads mustnecessarily be reknotted. The drawback of such an apparatus is, however,that only the size of the knot can be checked. This method is furtherinsufficient when, for example, a third thread becomes knotted incausing the knot to become about 50% thicker. However, in some cases thethread cross section is such that the knot formed of three threads issmaller than the average knot formed of two threads. For these reasonsan apparatus that determines only the size of the knot within a fairlysensitive range of sizes may cut out a great many knots that actuallyneed not be removed. However, if the sensitivity of such an apparatus isreduced, then while probably less knots are cut out unnecessarily, thepercentage of knots that ought to have been cut out but are not isexcessive.

The present invention avoids these drawbacks by providing a method forchecking knots in a traveling thread which comprises the steps ofproducing a first signal corresponding to a knot on a traveling thread,detecting the cross section of the traveling thread in the vicinity ofthe knot, producing a second signal in response to the detection of athread cross section in excess of a predetermined measured size,detecting the simultaneous presence of the first and second signals andsevering the traveling thread in the vicinity of the knot upon detectionof the simultaneous presence of the first and second signals.

3,371,568 Patented Mar. 5, 1968 Further, the present invention providesan apparatus for checking knots in a traveling thread which comprises afirst measuring device for producing a first signal corresponding to aknot passing therethrough, a second measuring device for detecting thecross section of the thread in the vicinity of the knot and forproducing a second signal in response to the detection of a thread crosssection in excess of a predetermined measured size, means responsive tothe simultaneous presence of the first and second signals for deliveringa third signal and means responsive to the third signal for actuating acutting device to sever the traveling thread in the vicinity of theknot.

Accordingly, it is an object of this invention to provide a method andapparatus for detecting the presence of a knot in a traveling thread andthe cross section of the thread in the vicinity of the detected knot.

It is another object of this invention to provide a method and apparatusfor removing a defective knot from a traveling thread.

It is another object of this invention to provide a method and apparatusfor removing a defective knot from a traveling thread upon simultaneousdetection of a knot in the thread and a thread cross section in excessof a predetermined size in the vicinity of the knot,

It is another object of the invention to provide an apparatus forchecking the presence of undesired knots in threads processed in textilemachinery, which apparatus comprises at least one first measuringdevice, for example, of the electrically capacitively operating typethrough which a thread is passed and which produces a signal whenever aknot passes through the device, at least one second measuring device,for example, also of the electrically capacitively operating typethrough which the thread is passed in series relation to the passage ofthe thread through the first measuring device, the second measuringdevice producing a signal whenever the cross section of the threadspassing through the second measuring device exceeds the cross section ofa single thread, anda means, for example, an AND gate, connected to themeasuring devices for receiving signals therefrom and adapted to beactivated only when signals produced by the measuring devices arereceived simultaneously from the measuring devices.

It is another object of the invention to provide a method and apparatusfor varying the time constant of the signal producing operations of theabove apparatus whereby the time constant is reduced when thread passageis initiated and is substantially increased when a signal is produced inresponse to the cross section of the passing thread or in response to apassing knot.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagrammatic illustration of a measuring zone arrangement,with a thread running through;

FIG. 2 is a diagrammatic illustration of a measuring zone arrangement,with .a knot running through;

FIG. 3 is a block diagram of an apparatus for the evaluation of thesignals produced in the measuring zone arrangement shown in FIGS. 1 and2;

FIG. 4 shows schematically a variant of the measurement zonearrangement;

FIG. 5 shows schematically another variant of the measuring zonearrangement; and

FIG. 6 shows a modification of the apparatus illustrated in FIG. 3.

In FIG. 1, a first measuring zone which may, for example, be formed bythe electrodes of a capacitively operating measuring device 1, asgenerally shown in US. Letters Patent Nos. 3,009,101 and 3,039,051, isspaced a short distance behind a second measuring zone formed by asecond measuring device 2 with respect to the direction of travel ofthread 4 therethrough. As shown, the thread 4 runs from left to right,in the direction indicated by the arrow, in passing through thesemeasuring zones. The thread shown includes a knot 41 which has a remnantthread 42 trailing behind it such as that which occurs when the knottingapparatus either does not cut completely through the thread ends, orwhen a third thread is carried along in the knotting apparatus withoutbeing embodied, so that it does not become cut off with the other threadends.

in FIG. 2 the knot 41 is shown advanced into the region of the measuringzone 1, while the remnant threads 42 is still in the effective measuringzone 2.

When a normal knot enters the measuring device 2 a signal is triggered.However, when the normal knot subsequently enters the measuring device 1a signal is produced only by the measuring device 1, a single threadbeing situated in the device 2. However, if the knot drags along aremnant thread 42, then measuring device 1 as well as the device 2 willemit signals simultaneously to indicate the presence of a defectiveknot, because the device 2 is set to be actuated by two threads 4 and 42when the knot 41 enters measuring device 1.

This simultaneous emission of two signals may be used, for example, forinitiating the cutting of the thread in the vicinity of the defectiveknot.

In order to be independent of the direction in which the thread runs,the first measuring zone may be duplicated on the other side of thesecond measuring Zone, such .an arrangement being shown by FIG. 4. Adefective knot is then indicated by a simultaneous signal produced bythe measuring device 2 and by at least one of the measuring devices 1'and 1".

Another way of making the apparatus independent of the direction inwhich the thread runs, is shown in FIG. 5. In this case, the secondmeasuring zone is duplicated. Here, a defective knot produces a signaleither at measuring device 2 or at measuring device 2", and also atmeasuring device 1.

FIG. 3 shows a block diagram of one example of carrying out theinvention. The two measuring devices 1, 2 form capacitive measuringsystems. They may, however, sense the thread thickness by optical,magnetic, radiationabsorbing or other means, and produce correspondingsignals.

High-frequency power for operating the measuring devices 1 and 2 issupplied by conventional high-frequency generators 5 and 6,respectively. It is also possible to use a single high-frequencygenerator in common for both measuring devices. Depending on thecapacity present in the measuring devices 1, 2 (i.e., volume of the yarnportion in the measuring zone), more or less high-frequency energy issupplied to working resistances 7, 8. The voltages at these resistancesare rectified in diodes Q, 10, respectively. A direct current voltage isfirst formed at condensers 11 and 12, through rectification of thehighfrequency voltage originating from the zero capacity of therespective measuring device, i.e., the capacity of the measuring devicewhen no thread is present therein; thereafter, upon introduction of athread in the measuring device an additional capacity is formed, andthus an increased high-frequency voltage at the working resistances 7,8; and finally, an additional voltage originator at the condensers 11,12 which voltage is proportional to the quantity of thread in therespective measuring device.

In order to make the direct current voltage caused by the zero capacityand any instabilities that may occur inefllective, the DC voltage isseparated through condensers 13, 14. The static zero potential reachespast resistances 15 and 16 to the input of the amplifiers 21, 22 in theconventional manner. The resistances 15 and 16 are provided withswitches 23, 24 which will be explained later. The output voltages ofthe amplifiers 21 and 22 arrive at conventional Schmitt triggers 25 and26, respectively. The Schmitt trigger 25 is set so that it tilts when aknot enters a measuring device 1. The Schmitt trigger 26 on the otherhand is adjusted in such a way that it tilts when two threads arepresent in a measuring device 2. The outputs from these Schmitt triggersare conducted to the input of a conventional AND gate 30. The output ofthe AND gate 30 is connected to the input of an end stage 31, which, forexample, actuates a thread cutting device.

In most cases continuous checking of the thread is not necessary. Itsutfices if an apparatus according to the present invention operatesafter the knotting operation. Many of the automatic spooling machinesreferred to at the outset have only one knotting mechanism for a numberof spooling locations. Thus, checking of the knots is assured if theapparatus cooperates with the knotting mechanism in such a way that thethread is guided so that at least the knot runs through theknot-checking apparatus. The knotting and checking operation is, forexample, effected as follows: seizing the two thread ends to be tied anddirecting the thread ends to the knotter; knotting; starting the crossspool; and passing the knot through the knot-checking apparatus.

As has been mentioned already, the condensers 13 and 14 serve toseparate out the DC voltage originating from the zero capacity of themeasuring devices. The time constant of the condenser 13 and ofresistance 15, and of condenser 14 and of resistance 16 must on the onehand be relatively small, one second, for example, in order to permitguide stabilization, for example, when the apparatus is started; on theother hand, this time constant should be great so that the voltage atthe condensers 13 and 14 does not lag unallowably from the instant ofthe entry of the single thread into the checking apparatus untilcompletion of the checking operation. In order to meet theserequirements, an apparatus as described below may be connected.

An additional Schmitt trigger 27, whose tilting limit is adjusted to afairly small response range, for example 10% of the mean value of thecross section of the thread passing through the measuring zones, isconnected in parallel with the Schmitt trigger 26 to tilt upon entry ofa thread into the apparatus. If desired, it can be connected in parallelwith the Schmitt trigger 25. Initially, in its untilted state theSchmitt trigger 27 energizes a relay 28 which includes two normallyclosed contacts 2'3 and 24. When the Schmitt trigger 27 tilts, the relay28 is deenergized and the two contacts 23 and 24 are opened. This meetsthe apparently contradictory requirement of a relatively small timeconstant at the entry of a thread, because switches 23 and 24 are closedand an extraordinarily great time constant after entry of a threadbecause the switches 23 and 24 are opening. Such an arrangement, thatmay, for example, be termed time constant changer, can be connectedahead of or after the amplifier, or ahead of and after the amplifier, inorder to separate the DC voltage originating from the zero capacity atthe input to the amplifier, and in order to eliminate instabilities inthe amplifier itself.

The apparatus according to the present invention can be adapted, withrelatively small expenditure, to solve additional problems. Thus, forexample, the size of the knot can be checked by connecting an additionalSchmitt. trigger 32 (FIG. 6) in parallel to the Schmitt trigger 25whereby the tilting limit of the trigger' 32 is adjusted to correspondto the permissible, size of the knot and the output of the trigger 32 isconnected directly to the final stage 31 for rendering the stageineffective upon passage of a knot of permissible size.

Having thus described the invention, it is not intended that it be solimited as changes may be readily made therein without departing fromthe scope of the invention. Accordingly, it is intended that the subjectmatter described above and shown in the drawings be interpreted asillustrative and not in a limiting sense.

What is claimed is:

1. A method of checking knots in a traveling thread comprising the stepsof producing a first signal corresponding to a knot in the travelingthread,

detecting the cross section of the traveling thread in the vicinity ofsaid knot,

producing a second signal in response to the detection of a thread crosssection in excess of a predetermined measured size, detecting thesimultaneous presence of the said first and second signals, and

severing the traveling thread in the vicinity of said knot upondetection of the simultaneous presence of said first and second signals.

2. A method as set forth in claim 1 which further comprises the steps ofdetecting the size of said knot and producing a third signal in responseto the detection of a knot size different from a predetermined measuredsize whereby the traveling thread is severed in the vicinity of saidknot upon production of said third signal and one of said first andsecond signals.

3. An apparatus for checking knots in a traveling thread comprising afirst measuring device for producing a first signal corresponding to aknot in the traveling thread passing therethrough,

a second measuring device upstream of said first measuring device fordetecting the cross section of the traveling thread in the vicinity ofsaid knot and for producing a second signal in response to the detectionof a thread cross section in excess of a predetermined measured size,

means responsive to the simultaneous presence of said first and secondsignals for delivering a third signal, and

means responsive to said third signal for actuating a cutting device toseverthe traveling thread in the vicinity of said knot.

4. An apparatus as set forth in claim 3- wherein said means responsiveto the simultaneous presence of said first and second signals comprisesan AND gate, said AND gate being opened on the simultaneous presence ofsaid first and second signals whereby the output thereof is delivered assaid third signal.

5. An apparatus as set forth in claim 3 which further comprises a thirdmeasuring device upstream of said second measuring device for producinga fourth signal corresponding to a knot in the traveling thread passingtherethrough whereby the traveling thread is severed upon simultaneouspresence of said second signal and at least one of said first and fourthsignals.

6. An apparatus as set forth in claim 3 which further comprises a thirdmeasuring device downstream of said first measuring device for detectingthe cross section of the traveling thread in the vicinity of said knotand for producing a fourth signal in response to the detection of athread cross section in excess of a predetermined measured size wherebythe traveling thread is severed upon simultaneous presence of said firstsignal and at least one of said second and fourth signals.

7. An apparatus as set forth in claim 3 which further comprises a meansfor detecting the size of said knot and for producing a fourth signal inresponse to the detection of a knot size difierent from a predeterminedmeasured size whereby the traveling thread is severed upon simultaneouspresence of said fourth signal and one of said first and second signals.

8. An apparatus as set forth in claim 3 wherein said first and secondmeasuring devices form a capacitive measuring system.

9. An apparatus as set forth in claim 8 wherein said first means andsaid second means each comprises a resistance-condenser element, and atime constant varying means connected to said resistance-condenserelements, said time constant varying means being capable of reducing thetime constant of said resistance-condenser elements when thread passageis initiated and of substantially increasing the time constant of saidresistance-condenser elements when a signal is produced -by one of saidfirst and second means.

10. An apparatus as set forth in claim 8 wherein said first and secondmeasuring devices include a condenser in the path of each of said firstand second signals, -a relay having a pair of contacts, each of saidcontacts being disposed in a respective path of said first and secondsignals downstream of a respective condenser, a pair of resistances,each of said resistances being connected to -a respective one of saidcontacts for operative connection into said respective paths of saidsignals, and means for triggering said relay upon entry of the travelingthread into said second measuring device whereby the time constant ofsaid condenser and resistance are changed upon passage of a threadthrough said first measuring device.

References Cited UNITED STATES PATENTS 3,039,051 6/ 1962 Locher 324-613,185,924 5/1965 Locher 32461 3,303,698 2/1967 Loepfe 324-61 X WILLIAMS. LAWSON, Primary Examiner.

